[11.02] The UH Near-Earth Asteroid Composition Survey: An Update

R.J. Whiteley, D.J. Tholen (University of Hawaii, IfA)

We present an update on our spectrophotometric survey of the
Near-Earth asteroids. From 1985 to 1992, approximately 100
NEA's were observed in the 8-color photometric scheme using
a photomultiplier system. From 1996 to 1999, we observed
another 100 NEAs, again in the 8-color photometric system,
this time using CCD technology. The basic end result of our
survey will be a catalogue of NEA taxonomies and whatever
rotational information can be discerned from our data. But
the driving purpose behind gathering such a large data set
is to do statistically meaningful checks on possible
correlations between the spectral properties and the
dynamical state of the NEA's. For example, several
researchers have reported color variations with absolute
magnitude [1,2,3].

We are interested in testing this assertion, of course, as
well as the potential correlation between the optical
principal components and perihelion distances of the NEA's.
If there is a temporal weathering sequence among the
chondrite/silicate NEA's, evidence for it may be found in
such a relationship. At the very least a lack of correlation
between perihelion distance and colors should allow us to
set lower limits on the time scales over which any
weathering process must occur. By the time of the Padua DPS
meeting, we should have on hand and available for review
spectral data on about 50 objects out of our total sample of
200. This will allow us to make some preliminary statistical
analysis of this idea, as well to check on the absolute
magnitude vs. color correlation.